Rookie manager Mike Redmond defers to his bosses when asked if Yelich could be on the opening-day roster.

"They might come down and tell me to quit playing him," Redmond said with a laugh. "It's fun to get him in there. You feel like any situation he comes up he's got a chance to do something, and he hits a home run to dead center to win it."

Even if Yelich is ready to break camp with the big league club, the Marlins may hold him back until late April to gain an extra year before he's eligible for free agency. If he was held back until about June, Miami would likely get an extra year before Yelich is eligible for arbitration.

The 21-year-old Yelich was Miami's first-round pick in 2010. The 6-foot-4, 189-pound left-handed hitter grew up in Thousand Oaks, Calif. A corner infielder in high school, he moved to the outfield in the minors and has been tabbed the Marlins' center fielder of the future.

Yelich's mother arrived from California last weekend to watch her son play. She has seen him homer in consecutive games — he went deep against the Atlanta Braves on Sunday before his game-winner against Boston.

"That was pretty cool — I don't really know what to say. You can't draw it up any better," Yelich said. "This is the second walkoff home run in my life. The first one was a playoff game at (Class-A) Greensboro two years ago."

What Yelich did on the game's final pitch, Boston's Jackie Bradley Jr. did on the game's first pitch: He homered off Kevin Slowey's first offering, and he reached base four times.

Bradley Jr. went 3 for 4 to raise his average to .519 (14 for 27). He added an RBI double in the fourth.

"As we get further into camp and pitchers are getting their timing down, he's still taking great swings and making good contact," Red Sox manager John Farrell said.

Lester allowed a first-inning run and three hits. He struck out four and retired the last 11 batters he faced.

"I feel pretty good, but I don't want to have everything clicking right now. I kind if want to build it up to that first start," Lester said. "I feel good, and that's the main thing."

Slowey gave up three runs and two hits in three innings as he fights to become Miami's fifth starter. He walked two and struck out five in his first spring start after previously throwing 6 1-3 scoreless relief innings.

NOTES: Miami OF Jake Marisnick is expected to be sidelined four weeks with a broken left hand. Marisnick was injured when hit by a pitch from Trevor Rosenthal in Wednesday's game against St. Louis. The break was discovered Monday after initial X-rays failed to show the injury. ... Boston reliever Rubby De La Rosa gave up five runs, four walks and two hits in 2-3 of an inning. He threw 36 pitches and walked in two runs. ... The Marlins optioned RHP Evan Reed, RHP Alex Sanabia, LHP Brad Hand, OF Kyle Jenson to Triple-A New Orleans (Pacific Coast League); RHP Sam Dyson, LHP Edgar Olmos, OF Marcell Ozuna to Double-A Jacksonville (Southern League); re-assigned RHP Jordan Smith & C Wilfredo Gimenez to minor league camp.